CN1491541A - Pesticide water-suspended nanocapsules and preparation method thereof - Google Patents

Abstract

The present invention discloses water suspended nano pesticide capsule preparation prepared via emulsion polymerization process. It has capsule shell of styrene, isocyanate, acrylate and methacrylate copolymer, and core comprising ididacloprid, high effect cypermethrin or diflubenzuron as effective component; contains pesticide 0.2-5 wt%, capsule shell 5-30 wt%, additive 10-35 wt% and water in proper proportion. The nano capsule is disersive spherical particle of size smaller than 100 nm. Compared with traditional pesticide preparation forms, the present invention has the features of water based solvent, nano level dispersive effective component, high stability, etc. and may be used in killing various pests of fruit tree, vegetable, flower, cotton, tobacco, etc.

Description

Pesticide water-suspended nanocapsules and preparation method thereof

technical field

The invention relates to a pesticide water-suspended nanocapsule, which belongs to the formulation technology of pesticides and veterinary drugs.

Background technique

Pesticide is a product obtained after chemical transformation of abamectin, and it is a semi-synthetic antibiotic pesticide pesticide. The efficacy against lepidopteran pests is significantly improved and the toxicity is lower than that of abamectin, and it is a new type of biological pesticide. Pesticide benzoate insecticide has the characteristics of ultra-high efficiency, non-toxic, pollution-free, double insect lethality, and less affected by environmental factors. Compared with other series products of abamectin, the activity against the thorny Lepidoptera pests in the agricultural world has increased by 1-3 orders of magnitude, and it can be used on economic crops such as vegetables, tobacco, and tea. The dosage is about 2-grams per hectare, which has a good control effect on pests. Its broad-spectrum, ultra-high efficiency, low dosage and low residue, and not easy to produce drug resistance determine that it will play an important role in the prevention and control of crop diseases and insect pests. The main dosage form of pesticides disclosed in the prior art is emulsifiable concentrate. As a traditional dosage form of pesticides, the control effect is acceptable, but there are the following problems:

1. Contains a large amount of organic solvents, such as toluene, xylene, etc., causing thousands of tons of organic solvents to be discharged into nature every year, wasting resources and seriously polluting the environment.

2. When used, it needs to be diluted with water to form an emulsion. The active ingredients are micron-scale dispersed. The dispersibility of the active ingredients is poor and the effective utilization rate is low, resulting in a large amount of pesticides, resulting in increased agricultural costs and a large amount of pesticide residues, which seriously affects the quality of agricultural products.

3. The active ingredient has poor permeability, and the active ingredient remaining on the leaf surface is decomposed and wasted due to environmental factors such as light and air.

4. The colonization of biological pesticides in the soil is poor, and the special ecological environment of the soil often inhibits the efficacy of biological pesticides, which limits the large-scale promotion of biological pesticides.

Compared with emulsifiable concentrates, microemulsions of pesticides can better solve the problems of water-based and high dispersion, but they are not long-acting dosage forms, cannot control the release, more importantly, the cost is high, and the effect is not ideal.

Contents of the invention

The object of the present invention is to provide a kind of pesticide water-suspended nanocapsules, which has the advantages of high dispersion, super high efficiency, long-acting, water-based, low cost, etc., and is a new dosage form of biological source pesticides and veterinary pesticides with better application effects .

The purpose of the present invention is achieved based on the following ideas. According to the principle of polymer particle formation, properly adjust the ratio of monomers, add additives, and control the reaction conditions during the emulsion polymerization process to obtain polymer particles with different internal structures, different shapes, and different particle sizes. Therefore, as long as the monomers and their proportions, additives, and reaction conditions are controlled, nanocapsule particles can be obtained.

Specifically, the composition of the pesticide water-suspended nanocapsules of the present invention is expressed as follows by weight percentage:

Pesticides: 0.2～5%

Mixed monomer: 5～30%

Additives: 15～35%

Initiator: 0.05～1%

    Deionized water   The balance

Wherein, the polymerizable monomers are vinyl monomers, acrylic monomers, methacrylic monomers and isocyanate monomers.

Additives are emulsifiers, dispersants and protective colloids.

The initiator is persulfate, azo or redox system initiator.

The number-average particle diameter of the capsules is less than 100 nanometers.

Vinyl monomer, acrylic monomer, methacrylic monomer and isocyanate monomer, can choose styrene, vinyl acetate, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid, methacrylic acid , methyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, N-methylol acrylamide, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene Base polyphenyl polyisocyanate, hexylene diisocyanate, etc.

Two or more of the monomers are used for polymerization to form the capsule skin.

The core of the capsule is the original pesticide.

Suitable emulsifiers are nonionic emulsifiers and anionic emulsifiers; nonionic emulsifiers can be selected from Tween, Span, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, etc.; anionic emulsifiers can be selected from dodecane Sodium sulfate, sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, etc. In order to control the number-average particle diameter of the capsules to be less than 100 nanometers, the emulsifier dosage is not less than 7%, preferably 7%-20%.

Suitable dispersants are polymethacrylates and polyacrylates, low molecular weight styrene-maleate copolymers.

Suitable protective colloids are many commonly used substances, which may be preferred: polyvinyl alcohols, sodium polyacrylates, methylcellulose, carboxymethylcellulose, pectates, gelatin, gum arabic, polyethylene oxide and other substances.

In the pesticide water suspension nanocapsules of the present invention, auxiliary agents can also be contained, and auxiliary agents are one or more of preservatives, defoamers and antifreezing agents, and their content is represented by weight percentage as accounting for 5-8% of the total composition. %.

Suitable preservatives are commonly used in polymer emulsions, such as sodium pentachlorophenate, o-chloro-m-cresol, tetrachloro-resorcinol.

Suitable defoamers are readily available products such as silane derivatives polydimethylsiloxanes, tributyl phosphate, polypropylene glycol, etc.

Suitable antifreeze agents include ethylene glycol, glycerin, propylene glycol, ethylene glycol butyl ether acetate, urea, sucrose, and the like.

The average particle diameter of the particles of the dispersed phase is 50 nanometers and not larger than 100 nanometers.

The aqueous phase of the nanocapsules of the present invention consists essentially of water and additives such as emulsifiers, dispersants, protective colloids and auxiliary agents, i.e. preservatives, defoamers and antifreeze agents, preferred components being those mentioned above. In addition, the aqueous phase may also contain minor amounts of components of the dispersed phase.

The composition of the nanocapsules of the present invention can vary within a certain range. In the system, the amount of the dispersed phase is generally 15-50% by weight, and the concentration of each substance in the dispersed phase is as follows (by weight):

Mixed monomer 5-30%;

Pesticide active substance pesticide 0.2-5%;

Additives are generally 10-35%, preferably 12-25%.

The preparation method of pesticide water-suspended nanocapsules of the present invention comprises the following steps:

(1) Initiator is dissolved in deionized water, stand-by;

(2) Pesticides are mixed with monomers and additives;

(3) The resulting mixture is dispersed in water under high-speed stirring to form an emulsion;

(4) Heat the emulsion to 50-90°C, add an aqueous initiator solution, react for 1-16 hours, and keep warm for 0.5-3 hours;

(5) Add additives, cool down and discharge.

For the preparation of emulsions, a number of devices suitable for generating strong shear forces are available.

The process of the present invention is usually carried out under normal pressure.

The nanocapsules of the present invention need to be diluted with water in actual use, and applied by conventional methods, for example, by spraying.

The nanocapsules and usage amount of the present invention can be changed within a certain range, depending on the subject to be administered and the content of methamacin in the nanocapsules.

Compared with the prior art, the technical progress achieved by the present invention lies in:

1. The particle size is very small and the surface tension is low, so it has excellent permeability, wettability, leveling and rheology, and can directly penetrate into the fine capillary channels of plants; its particle number average particle size is less than 100 The nanometer is only one thousandth or smaller than the microcapsule, which can make the pesticide highly dispersed.

2. The stability of nanocapsule particles depends on the electric double layer of the capsule wall itself, which is a kind of chemical bonding force. Compared with the dispersion mechanism of microemulsion, the stability is improved.

3. The solvent is water, so the pollution is small and the cost is reduced.

4. It has the function of controlled release, prolongs the duration of the same dose of pesticides, improves the utilization rate of pesticides, reduces the dosage of pesticides, and thus reduces the pollution of pesticides and pesticides to the environment.

5. It inhibits the decomposition and loss of medicine caused by environmental factors (such as light, heat, rain, soil, microorganisms and other chemical substances), improves the stability of the medicine itself, and is beneficial to the ecological environment.

6. Reduce acute toxicity, phytotoxicity and fish toxicity.

Pesticide water-suspended nanocapsules comprehensively solve the problems of water-based, highly dispersed, stable and long-acting capsules of preparations. Its efficacy is higher than other dosage forms and its cost is lower than other commonly used dosage forms, so it has important promotion Value.

Detailed ways

The invention is illustrated by the following examples.

Embodiment one:

0.1g ammonium persulfate is dissolved in 20g water (divided into two parts by 4:1), stand-by; 0.5g pesticide active substance is dissolved in the mixed monomer of 7g styrene, 8g butyl acrylate, 0.2g acrylic acid; Dissolve 6g of OP-40 and 1g of sodium lauryl sulfate in 50g of 2% polyvinyl alcohol aqueous solution, put them in a stirring container, add the mixed monomers with pesticide active substances under stirring, and disperse into an emulsion , into the reaction vessel. Heat to keep the temperature at 70±2°C, add the first part of initiator, react for 6 hours, keep warm for 1 hour, and prepare the seed emulsion; add 1.5g of styrene, 1.5g of butyl acrylate, 2g of toluene diisocyanate mixed monomer and Add the second initiator dropwise for 1 hour, keep warm for 2 hours, cool down; add additives, and discharge. The content of pesticide active substance in the product is 0.5%.

Embodiment two:

Dissolve 0.1g potassium persulfate in 10g water (divided into two parts according to 4:1), 1g acrylamide is dissolved in 10g water, stand-by; dissolve 1g pesticide active substance in 4g ethyl acrylate 7g butyl acrylate mixed monomer In; 5g OP-40, 4g sodium lauryl sulfate, 4g sodium polymethacrylate are dissolved in 60g water, put into a container with stirring, under stirring, add the mixed monomer that is dissolved in pesticide active matter, Disperse into an emulsion and put it into a reaction vessel. Heat and keep the temperature at 70±2°C, add the first initiator and acrylamide aqueous solution, react for 6 hours, keep warm for 1 hour, and prepare the seed emulsion; add 1g ethyl acrylate, 1g butyl acrylate, 2g 4,4' dropwise - diphenylmethane diisocyanate mixed monomer, dropwise for 1 hour, keep warm for 2 hours, cool down; add additives, discharge. The content of pesticide active substance in the product is 0.9%.

Claims (6)

1. Pesticide water-suspended nanocapsules, characterized in that, the composition is by weight: Pesticides: 0.2-5% Mixed monomers: 5-30% Additives: 10-30% Initiator: 0.05-1% De-particle water: balance Wherein, the mixed monomers are vinyl monomers, acrylic monomers, methacrylic monomers and isocyanate monomers. Additives are emulsifiers, dispersants, and protective colloids. The initiator is persulfate type, azo type or redox system initiator. The number-average particle diameter of the capsules is less than 100 nanometers. 2. The pesticide water-suspension nanocapsule according to claim 1, characterized in that the composition contains auxiliary agents, and the auxiliary agents are one or more of preservatives, defoamers and antifreeze agents, and their content is expressed in weight percent It is 5-8% of the total composition. 3. The pesticide water suspension nanocapsule according to claim 1, characterized in that: the mixed monomer is selected from two or more of the following substances, which are: styrene, acrylonitrile, methyl acrylate, Ethyl acrylate, butyl acrylate, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, N-methylol acrylamide, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, Polymethylene polyphenyl polyisocyanate, hexylene diisocyanate, etc. 4. The pesticide water-suspension nanocapsule according to claim 1, wherein the emulsifier is a nonionic or anionic emulsifier, and the nonionic emulsifier is selected from Tween, Span, nonylphenol polyoxyethylene ether, octyl Phenol polyoxyethylene ether; the anionic emulsifier is sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate; the dispersant is polymethacrylate, low molecular weight styrene-cis A copolymer of butenedioate; the protective colloid is polyvinyl alcohol, sodium polyacrylate, methylcellulose, carboxymethylcellulose, pectate, gelatin, gum arabic, polyethylene oxide, etc. 5. The pesticide water-suspension nanocapsule according to claim 2, wherein the preservative is sodium pentachlorophenate, o-chloro-m-cresol or tetrachloro-m-cresol; the defoamer is polydimethylsiloxane Oxyalkylenes, tributyl phosphate, polypropylene glycol; antifreeze agent selection ethylene glycol, glycerin, propylene glycol, ethylene glycol butyl ether acetate, urea, sucrose. one or more of them. 6. A method for preparing pesticide water-suspended nanocapsules, characterized in that it comprises the following steps: (1) initiator is dissolved in deionized water, stand-by; (2) Pesticides are mixed with monomers and additives; (3) The resulting mixture is dispersed in water under high-speed stirring to form an emulsion; (4) Heat the emulsion to 50-90°C, add an aqueous initiator solution, react for 1-16 hours, and keep warm for 0.5-3 hours; (5) Add additives, cool down and discharge.